Electrical device



July 12, 1960 R. K. GESSFORD ELECTRICAL DEVICE Filed April 30, 1958 1101...) kid a! JEN.

INVENTOR ROSS/(655m EMZCfiZI A'ITORNEY ELECTRICAL DEVICE Ross Gessford, Seneca Falls, N.Y., assiguor, by mesne assignments, to Sylvania Electric Products Inc., Wilmmgton, Del., a corporation of Delaware Filed Apr. 30, 1958, Ser. No. 732,045 2 Claims. (Cl. 313-418) This invention relates to electrical devices and more particularly to the stern construction of such devices.

Generally, the stem of an electrical device such as a cathode ray tube comprises a bell-shaped header having electrical leads passing therethrough for connecting electrodes arranged within the neck of the tube with appropriate external electrical circuits. A cylindrical insulating base having a closure member formed with apertures for allowing passage of the leads therethrough is telescoped over the header and a portion of the tube neck. A construction of this type is expensive to fabricate and has sufiicient size to hinder the trend toward the production of tubes having shorter neck lengths.

Accordingly, an object of the invention is to provide a relatively inexpensive easily assemblable stem construction for electrical devices.

A further object is the provision of a unique stem construction employing a protective cap for the exhaust tubulation of an evacuated electrical device.

The foregoing objects are achieved in one aspect of the invention by the provision of a unique stem for electrical devices employing an exhaust tubulation projecting from the header and employing a cylindrical cap formed to substantially enclose the tubulation. The header has an indexing protrusion formed thereon which meshes with an internal recess provided in the cap. An ex ternally disposed key formed on the peripheral surface of the cap aligns auxiliary circuit connectors with appropriate stem leads of the electrical device.

For a better understanding of the invention reference is made to the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a plan view of an electron gun and stem construction of a cathode ray tube;

Fig. 2 is a portion of the stem shown in Fig. lillustrab ing an indexing protrusion;

Figs. 3, 4 and 5 illustrate the cylindrical cap used to substantially enclose the exhaust tubulation formed as part of the stem;

Fig. 6 shows the cylindrical cap in assembled position around the exhaust tubulation, and

Fig. 7 shows a conventional electrical socket.

Referring to the drawings, an electron gun 11 is shown mounted within neck portion 12 of a conventional cathode ray tube for purposes of illustration. The gun comprises a heater 13, cathode (not shown), first grid 15 and a second grid 17. The gun also employs an electron beam accelerating and focusing assembly 19. These electrodes are mounted relative to one another by means of insulating rods 21. The electrodes are electrically connected to their respective sources of potential by means of electrical leads 23, straps 25 and connectors 27.

Electron gun 11 is mounted upon header 28 of stem 30 by means of leads 23, which pass through the glass header and terminate in exterior pins 29. Generally, leads 23 are connected to the pins and are hermetically sealed with the glass of header 27 by means of an appro- 2,945,148 Patented July 12;, 19 0 ice priate metal alloy having a coeflicient of expansion comparable to that of the glass employed. An exhaust tubulation 31 projects from the center portion of header 27. After evacuation of the cathode ray tube, the tubulation is tipped-ofi' to provide a vacuum tight seal 33, which is generally located below the ends of pins 29.

Fig. 2 shows in detail the structure of the wafer-shaped header 28 and exhaust tubulation 31. The header is formed with a substantially V-shaped indexing protrusion 35. Generally, during fabrication of the stem, the header is first formed as a wafer, tubulation 31 is subsequently connected thereto during a heating operation, and an opening is then formed through the header into the tubulation. Therefore, indexing protrusion 35, which is arranged radially on the exterior surface of the header, tends to follow the juncture 37 formed between the glass of the header and the glass tubulation while a seal between these components is being made. Due to this seal, indexing protrusion 35 tends to extend across the curved juncture area 37 and radially across header 28 to a point spaced from the outside edge thereof.

In order for the electrodes of mount 11 to be easily and correctly connected with their appropriate external circuits, it is necessary to employ means whereby the proper exterior pins 29 connect with the appropriate portions of a conventional socket 32. In accordance with one aspect of the invention, the circuit orienting feature is provided by means of a cylindrical cap 39 having a longitudinal key 41 and a substantially V-shaped internal recess 43. The cap is formed to be afiixed to and substantially enclose tubulation 31. Recess 43 is aligned with indexing protrusion 31 during assembly of cap 39, and these elements are meshed with one another as the leading edge of the cap substantially abuts the lower surface of header 28. Since protrusion 35 is positioned in a prescribed manner on the header, the cooperation between this protrusion and recess 43, acting in conjunction with key 41, provides means for orienting the stem relative to the socket 32 to which it is conventionally connected. Although the internal recess 43 has been shown as extending to a position spaced from the edge of cap 39, it is to be understod that the recess may extend completely down the wall of the cap, if desired. Also, the recess may be formed interally of the surface of cap 39 at a location other than on the oppositely disposed surface from key 41.

Fig. 6 illustrates a portion of the stem assembly comprising header 28 and cap 39, which is disposed centrally of the peripherally arranged exterior pins 29. The cap may be afiixed to exhaust tubulation 31 by means of a cement such as an epoxy resin which hardens upon baking above approximately F. When the cathode ray tube is being electrically connected to its supply, key 41 of cap 39 is slid into keyway 45 of socket 32 and pins 29 are thereby aligned with the appropriate connectors located within apertures 47.

Although several embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein Without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

l. A stem for an electrical device having a plurality of electrodes comprising a header having electrical leads passing therethrough formed to provide electrical connections for the electrodes, said leads terminating in exterior pins, an exhaust tubulation projecting exteriorly from a junction with said header and disposed intermedi ate said pins, an exteriorly arranged indexing protrusion formed on said header terminating at the juncture, and a cylindrical cap attached to and substantially enclosing 3 said tubulation only, said cap being formed with an internal recess for meshing at the juncture with said protrusion.

2. A stem for an electrical device having'aplurality of electrodes comprising a header having electrical leads passing therethrough formed to provide electrical connections for the electrodes, said leads terminating in exterior pins arranged peripherally around said header, an exhaust tubulation projecting exteriorly from a juncture with said header disposed centrally of said pins and extending beyond the ends thereof, an exterior radially arranged indexing protrusion formed on said header terminating at the juncture, and a cylindrical cap attached References Cited in the fi le of this patent UNITED STATES PATENTS 2,339,402 Herzog -2 J an. 18, 1944 2,451,847 Madden -e Oct. 19, 1948 FOREIGN PATENTS 59,753 Denmark Apr. 27, 1942 133,726 Australia Aug. 1, 1949 

